Combined time records interpretation in open hole and cased wells of gas and condensate fields, when complex neutron methods – 3-probe spectral neutron-gamma logging or 2-probe neutron logging – are used, opens a principal way to identify reservoirs with predictable permeability, saturation patterns, and hydrocarbons phase equilibrium. Gas or oil saturation factor change is a diagnostic indicator for phase conditions in well bore zone. Time records interpretation also uses open hole well logging. Applied to mature fields, reservoir saturation and phase patterns could be successfully defined by gas saturation changes. These and other logging data interpretation issues, methods and tool configurations are discussed in this paper.